Palaeont. afr. , 37, 103-113 (2001 )

NEW EVIDENCE OF THE GIANT HYAENA, PACHYCROCUTA BREVIROSTRIS (CARNIVORA, HYAENIDAE), FROM THE GLADYSVALE CAVE DEPOSIT (pLIO·PLEISTOCENE, JOHN

NASH NATURE RESERVE, GAUTENG, SOUTH AFRICA)

by

Raoul J. Mutter!, Lee R. Berger and Peter Schmid3

J Pakiontologisches Institut und Museum der Universitiit Zurich, Karl Schmid-Str. 4, 8006 Zurich, Switzerland, e-maiZ' rmutter@pim.unizh.ch

2 Palaeoanthropology Unit for Research and Exploration, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050, South Africa, e-maiZ' 106Irb@cosmos. wits.ac.za

3Anthropologisches Institut und Museum der Universitiit Zurich-Irchel, Winterthurerstr. 190, 8057 Zurich, Switzerland, e-maiL smidi@aim.unizh.ch

ABSTRACT A well preserved cranium which represents the most complete skull of Pachycrocuta brevirostris

(Carnivora, Hyaenidae) discovered in Africa, and a maxillary fragment from the Gladysvale Cave Deposit (John Nash Nature Reserve, Gauteng, South Africa) are described and compared to other fossil and extant hyaenid specimens from South Africa and Europe. In addition, some aspects of functional morphology in the hyaenid dentition are reconsidered and suggested to be directly related to the palaeoecological role of P. brevirostris.

KEYWORDS: Plio-Pleistocene, Pachycrocuta brevirostris, morphology, functional morphology, palaeoecology, South Africa, Europe.

INTRODUCTION In 1954, Ewer described the fairly complete cranium

KA-55 from the Kromdraai A Deposit and named the new species Hyaena bellax (Ewer 1954b). Sixteen years later the suggestion was made that this specimen be assigned rather to the genus Pachycrocuta (Ficcarelli & Torre 1970), known from several sites in Eurasia. At least two species of Pachycrocuta are known in Europe, P. brevirostris and P. perrieri (Werdelin & Solounias 1991; Guerin & Patou-Mathis 1996), and the two taxa are distinguished by metric tooth features (Werdelin & Solounias 1991: 22). Howell & Petter (1980) have pointed out close affinities between P. bellax and the comparatively well known Eurasian specimens of P. brevirostris and P. perrieri. This view was also supported by Turner (1986, 1987, 1988, 1990; Turner & Anton 1996), who had originally postulated close affinities between Pachycrocuta and Hyaena. Howell & Petter (1980) favored a two-lineage theory: P. pyrenaica - P. perrieri / P. brevirostris / H hyaena. Ficcarelli & Torre had proposed a similar theory in 1970, although their analysis relied on different features . Further studies including all hyaenids (Werdelin & Solounias 1991) led to H brunnea being placed in the new genus, Parahyaena, because of the lack of shared synapomorphies with H hyaena.

Currently, . research interests have shifted to the question of attributing a palaeoecological role to the giant hyaena Pachycrocuta in the Plio-Pleistocene. Turner & Anton (1996) have offered initial concrete conclusions from its fossil record. From this same perspective, an initial comprehensive study of new East

African material (Turkana Basin, Kenya) has contributed interesting insights (see Werdelin 1999). On the basis of new material from the Gladysvale Cave Deposit (Gauteng, South Africa) assigned to P. brevirostris, we examine and review certain morphological aspects and discuss the palaeoecological implications.

MATERIAL AND METHODS (List of abbreviations on page xxx) BPI: GV 3914 Pachycrocuta brevirostris (fairly complete cranium with dentition: p2, p3, P4, Ml sin. et dext.), dump 8, block 1, collected 28.4.1996. BPI: GV 4264 Pachycrocuta brevirostris (left maxillary fragment with dentition: p2, P3, fragmentary P4), dump 8, collected 9.10.1996. Locality: Gladysvale Cave Deposit (John Nash Nature Reserve, Gauteng, South Africa) Age: approximately 1.0 million years

Comparative fossil material NMB: Se 279 Pliocrocuta perrieri (Croizet &

Jobert 1828) (skull and dentition: pI, p2, Ml dext., p3, Ml sin.). St.V. 974 Euryboassp. (cranium, dentition: p2, p3, p4, Ml sin. et dext., upper C, P, F, P dext.), V.A. 2005 Pachycrocuta brevirostris (Hyaena robusta Le Ville 1921: cranium, dentition: pI, p2, P3, p4, Ml sin. etdext.). V.A. 65 Pachycrocuta brevirostris (Hyaena robust a LeVille 1921: cranium, dentition: P, pI, p2, p3, p4, Ml dext., upper C sin. fragmentary, P sin. fragm. p3 sin. fragm.)

104

TM: KA 55 Pachycrocuta brevirostris (Hyaena bel/ax Ewer 1954b) (left half of a cranium with articulated mandible, right maxillary fragment, dentition).

BPI: M 2530 Parahyaena brunnea. M 2567 cf. Chasmaporthetes. M 299, M 8348, M 245, M 248, M 254, M 8297, M 8925, M 2560, M 2587, M 8295, M 253 Hyaena makapani.

TM: KA 56 Crocuta spelaea capensis, KA 58 and KA 60 Crocuta ultra, SK 314 Hyaenictis, SK 326 Parahyaena brunnea dispar, Sts 128 Crocuta crocuta, Sts 129 hyaenid indet., Sts 135 Euryboas silberbergl~ SF 376 Pachycrocuta brevirostris.

Comparative extant material Hyaena hyaena . ZMUZ: 10155, 10156, 10157, 17510. FIS: 1158, 1356, 4273,4578,6729,4644,4645,1158,1356,15687,15689, 15690,15691,32782,63952,15687 Uuvenile).

Parahyaena brunnea FIS: 15684,6926.

Crocuta crocuta ZMUZ: 12258, 13096, 13097, 13098.SI:4579, 16358 Uuvenile). MS: ZA 1147M9, 162 Uuvenile).

Measurements were taken with calipers to the nearest 0.1 millimeter several times and averaged each time. Where possible, measurements were taken buccally. Terminology follows current literature.

SYSTEMATIC PALAEONTOLOGY Order CARNIVORA Bowditch, 1821

Family HYAENIDAE Gray, 1869 Genus Pachycrocuta Kretzoi, 1938

Pachycrocuta brevirostris (Aymard, 1846)

Synonymy: see Werdelin & Solounias (1991: 23), Turner & Anton (1996) and Werdelin (1999).

DESCRIPTION GV 3914 (Figures 1-5, measurements see Table 1)

The cranium The cranium consists of a large and broad hyaenid

skull belonging to a relatively old individual (Figures 1-4). The upper jaws, the anterior portion of the cranium and the left zygomatic arch are preserved. The latter increases considerably in depth and massiveness while projecting dorsolaterally. In ventral view, the zygomatic arch appears trapezoidal in outline (Figure 2). The posterior portion of the frontals and the palate, plus a major part ofthe left maxilla, including the infraorbital foramen, are penetrated, distorted, shifted or destroyed by calcite crystals containing breccia infill. The original vaulting of the palate cannot be directly observed, but there are longitudinal crevices on the left and right palatine, suggesting that considerable vaulting was originally present and was at least comparable to the condition usually stated for C crocuta.

sq

n

Figure lA, B. Dorsal view of the skull of Pachycrocuta brevirostris (GV 3914). Hatch lines indicate breccia infill. The scale bar equals 5 cm.

105

apf bs

izf calveole if

pm

Figure 2A,B. Pachycrocuta brevirostnsskull (GY 3914) in ventral view. Stippled lines indicate the probable course ofthe sutures. Wear facets are blank (Figure B). The scale bar equals 5 cm.

The postorbital processes of the jugals are large, oriented vertically and project slightly forwards rather than backwards. Below the orbit, the dorsal border of the jugal is flat and sloped, and reaches far anteroventrall y.

All sutures in the specimen differ in accordance with their state of preservation or, in some cases, because of their ontogenetic development. Although some sutures in the forehead can be traced easily, their preservation in the palate is such that it is often impossible to distinguish between bone margins and fine cracks. Nevertheless, we include their most probable courses, using dotted lines (Figure 4). The maxilla-frontal suture reaches further posteriorly than in extant hyaenids. Unfortunately, the nasals are too imperfectly preserved to be measured accurately; they are comparatively long and broad relative to the width of the skull. In lateral view, the frontals slope down less abruptly than in extant hyaenids and the face is characterized by an upwardly tilted forehead.

The posterior portion of the maxilla and the posterior part of the jugal form the well developed cheek region, which bears a conspicuous impression between the roots of the upper p4 (dented area of at least one square centimetre, compare Qiu 1987: 53).

The incisive foramina lie at the level of the anterior portion of the canine alveole and the incisive fossa reaches almost as far to the posterior as the hindmost point of the root of the second premolar. PremaxiUa­maxilla sutures pass near the posterior end of the incisi ve foramen. The foramen incisivum is narrow at its posterior end, compared to extant Hyaena and

Crocuta. An index of the foramen palatinum anterior length versus fossa palatina length would be advantageous, but cannot be given. Judged from the position of the foramen palatinum anterior, there is greater similarity to the 'crocutoid' than to the 'hyaenid' type (compare Qiu 1987: 62).

The jugal-maxilla suture describes a regular curve some distance from the orbita in the rostral portion. The posterior course is more difficult to trace, but both features seem to be 'crocutoid'.

The dentition (Figure 5) All teeth are heavily worn. Ml is placed obliquely

rather than perpendicularly in relation to the longitudinal axis of p4. From p4 to p2 the buccal outline describes a regularly curved line. The long axes of the two fourth premolars are almost parallel to each other.

Ml Three distinct cusps have probably been developed.

The upper first molars were worn down to a considerable extent by the talonid ofMl, and their overall state of preservation is too imperfect to allow detailed description.

p 4

The p4 is relatively broad; the meta style blade runs just offline from the longitudinal tooth axis. It forms nearly a right angle with the longitudinal axis of the comparatively large protocone. The protocone is large and shorter than the parastyle, which in turn is not as long as the metastyle (see Table 1). The paracone cusp

TABLE 1. Summary of comparative measurements in the skull and upper dentition (in mm), taken fromPocAycroc1llo 6reJ'iroslTirfrom Gladysvale specimens GV 3914, GV 4264, and

from Kromdraai specimenKA 55. * = approximate value.

p2 wll=ratio x 100 p3 wll=ratio xl 00 p4 wll=ratio x 100 p4 protocone diameter p4 protocone wll=ratio x 100 p4 protocone shape p4 parastyle p4 parastyle length p4 paracone length p4 metastyle length p2 anterior cusp p3 anterior cusp p3 posterior cU3P tooth row p2_p (length) p2 cingulum lingual shape of cingulu~ in general distance mx/j - P alveole border Ml wll distance inf - averaged alveole heigth p3 minimum width of snout depression above p4 position of inf anterior vertical edge of p3 cingulum bucc~ly skull length (P - posterior end of zyg.) max. canine alveole diamster distance orbit - alveole P length of orbit (measured parallel to tooth row)

GV3914 1l.9119.0=62.8 17.9*126.7=67.0 22.5/38.4=58.6 at root 6.9 7.6/9.1=83.5 massive, projecting far anteriad less massive than GV 4264 (wear?) 12.0* 12.4* 14.0* no notch, less prominent than GV 4264 no notch, more or less incorporated into main cusp distinct, but smaller than GV 4264 more curved than GV 4264 (8l.2) curvature pronounced intermediate 21.0* 6.9119 .9 25.5 at height of pi present at height between roots of p3 faintly developed, more linguo-posterior faintly developed 170.0* 21.0* 45.0* 33.9*

GV 4264 12.0117.5=68.6 17.0126.0=65.0 21.9J? at root 5.7 6.0*/8.0*=75.0 slender, projecting less far anteriad massive, anteriorly swollen • not preserved not preserved not preserved separated by a notch from the main cusp separated by a notch from the main cusp larger than GV 3914 faintly curved (80.0*) curvature pronounced sharp edged 300* Ml ?present 26.3* at heigth of p2 present at height of posterior part of p3 developed more anterior more prominent ? ? ? ?

KASS 12.7118.5=68.7 18.0125.4=70.9 21.4/39.3=54.5 at root 6.5 7.0/9.2=76.1 as GV 3914 as GV 4264 ILl * 13.1 * 15.1 * as GV 4264 as GV 4264 as GV 4264 or more pronounced intermediate (81.5) curvature less pronounced rounded 23 .0* ?/16.0* 25 at heigth of pi not present at height of posterior part of p3 as GV 3914 as GV 4264 168 19.5* 37.0* 37.6*

...... o '"

107

pm

Figure 3A,B. Right lateral view ofthe skull of Pachycrocuta brevirostris (GV 3914). Outline restoration based on recent Crocuta crocuta specimens and on Turner & Anton (1996, Figure 2) . Note the small orbit, the upwardly orientated face and the relatively short zygomatic arch. The scale bar equals 5 cm.

f

sq

5

Figure 4A,B. Outline sketch of the skull of Pachycrocuta brevirostris (GV 3914) in left lateral view, showing the reconstruction of the sutures on the zygomatic arch (Figure B). The scale bar equals 5 cm.

projects slightly posteriad. On the lingual wall of p4 the cingulum is weakly developed and, although worn off, appears to have persisted from the protocone to the posterior end of the metastyle. In buccal view the longitudinal grooves on the enamel diverge between metacone and paracone, paracone and parastyle. The anterior wear facet of the paracone of p4 (as described by Ewer 1954a: 189) is present and very small. The anterior obliquely inclined part of the wear facet of the protocone is worn down considerably by the paraconid and the main cusp of lower p4 (see Figure 5A,B).

p3

The p 3 is rather slender, and within the tooth row its longitudinal axis forms an angle of about 25 degrees with the longitudinal axis of P4. The posterior cusp is clearly separated from the cingulum and moderately large. Between the main and the posterior cusp is a vestigial, oblique groove.

p2

The p2 is fairly large and its longitudinal axis within the tooth row forms an angle of about 45 degrees with the longitudinal axis of p4. The posterior cusp is damaged, whereas the anterior is moderately developed and the lingual cingulum between the two roots is considerably curved (not figured).

Only the alveoli of pi, not the teeth, are preserved (see Figure 2).

GV 4264 (Figures 6-8, measurements see Table 1) This specimen consists of a left maxillary fragment

belonging to an adult individual, including the infraorbital foramen and part of the dentition with p2, p3 and a fragmentary p4 preserved (Figure 6-8).

On the maxilla above the roots of p4 is a depression similar to that in GV 3914. The minimum width of the snout is measured more toward the posterior (see Table 1). All teeth are less heavily worn than in GV 3914. Compared to GV 3914, the second premolar is smaller

108

A

c

Figure 5.

2cm

Illustrations of A. lingual , B. buccal, and C. occlusal aspects of the left upper tooth row (P2 - MI) of Pachycrocuta brevirostris as preserved in GV 3914.

relative to the third, and the premolar side cusps are much more prominent. When compared to the equivalent features in GV 3914, the P4 extends further anteriorly, but this difference is probably due to wear in GV 3914 (Figures 7/8).

In the p2 and p3, the lingual cingulum and all accessory cusps are more prominently developed than in GV 3914. The main cusp of the p3 is more slender and smaller, while the anterior accessory cusp is positioned more anteriorly than mesially compared to GV 3914.

Only the pi protocone and parastyle are preserved. The parasty Ie appears to have been slightly smaller than in GV 3914, although no accurate measurements could be taken. The protocone is considerably smaller than in GV 3914 (see measurements in Table 1). In lateral view the infraorbital foramen lies exactly above p3, and the minimum width of the snout is measured across the anterior palatine foramina. Unfortunately, the fossae for the inferior oblique muscles are not preserved.

The curvature of the upper tooth row is much less pronounced in GV 4264 than in GV 3914.

In overall size, GV 3914 exceeds GV 4264 slightly.

Additional remarks We did not observe the kind of wear facet preserved

in GV 3914 protocone in any other fossil or extant specimen (Figures 5Aand5B). In KA-55, GV 3914, and GV 4264 the P4 parastyle is worn off in various ways,

3cm

Figure 6. Lateral view of Pachycrocuta brevirostris maxillary fragment with p2, p3 and anterior portion of p4 in specimen GV 4264.

Figure 7. Pachycrocuta brevirostris (GV 4264), upper premolar tooth row as preserved in A. lingual, B. buccal, and C. occlusal views. The scale bar equals 2cm

B

c

Figure 8. Pachycrocuta brevirostris. Line drawings of specimen GV 4264; upper premolar tooth row as preserved in A. lingual, B. buccal, and C. occlusal views. Note the size of the accessory cusps in relation to the main cusps in premolars 2 and 3.

making comparison difficult. In KA -55 the anterior wall is least worn off and therefore gives the impression of a comparatively large parastyle.

Non diagnostic characters in Gladysvale specimens attributed to

Pacllycroculll IJre"irostris There is a wide range of interpretations in the

literature concerning the taxon-specific characters in fossil and extant hyaenids (see e.g. Qiu 1987: 59-67). Based on our comparative studies of fossil and extant hyaenids, we would suggest that, among the characters described in the South African specimens assigned to Pachycrocuta brevirostris, the following probably represent geographic or individual variation and should not be regarded as diagnostic features at the species level: 1. lingual cingulum is either sharply edged or rounded; 2. buccal cingulum variably pronounced; 3. varying massiveness ofP2 and p3 posterior side cusps

(see Table 1); 4. p2 and p3 anterior basal cusps variably distinct from

paracones; 5. varying size of p4 protocone in relation to p4

parastyle; 6. varying curvature of tooth row;

109

7. varying distance between ventral border of orbit and alveolus of p4;

8. absence or presence of maxillary depression between roots of P4.

Discussion of diagnostic characters Parahyaena brunnea and Pachycrocuta perrieri

share certain features, but whether these in fact represent primitive retentions (Werdelin & Solounias 1991) or diagnostic characters (Turner 1990) is controversial, and the significance of certain morphological differences in the dentition remains unclear. Furthermore, taxonomic difficulties, which of course are directly related to this problem, render what would appear to be a simple generic assignment debatable (see e.g. Turner 1986: 208, 1987: 326).

Occasionally, in hyaenid taxonomy it may be a matter of interpretation whether to keep two samples in separate taxa or to unite them within the same taxon on the basis of considering 'only' dental characters. Examples can be found in Pliohyaena pyrenaica orientalis Qiu 1987 and Pliocrocuta perrieri (Croizet & Jobert, 1828)(seeWerdelin& Solounias 1991; Guerin ~ Patou~Mathis 1996). The wide variety of mterpretatIOns also reflect taxonomic discrepancies, because groupings based merely on tooth size differences are heavily dependent on the sample chosen for comparison. From the available data, it must be concluded that intraspecific variation within samples is of considerable importance. Interestingly, if compared to other P. brevirostris samples from Eurasia, many ~outh African fossils fall at the lower range of variability m ~o~th m~asurements (Figure 8, but see Randall 1981 ). It IS m thIS context that the status of P. perrieri (see Kurten 1956: 42) must be considered. P. perrieri is reported to be changing slightly in the course of its evolution and trending towards Pachycrocuta brevirostris (Werdelin & Solounias 1991: 22). Apart from absolute size, the only distinguishing feature between the two species is reported to be in the M metaconid, which is always absent in P. perrieri (se~ Werdelin & Solounias 1991: 63). As already stated by Ko~fos (~992: 28), the length of the p4 metastyle is quite varIable m P. brevirostris. Evidently, the taxonomic importance of what is most probably a polymorphic character has to be questioned in P. brevirostris, since this cusp is present in only four out of29 specimens listed by Turner & Anton (1996); its mere presence therefore may indicate intraspecific variation. The solution to this problem may require reinvestigating the considerable dental variation within all P. perrieri samples - a task which is beyond the scope of the present study.

New east African remains from the Turkana Basin in Kenya were reported and compared to some of the known Eurasian P. brevirostris samples (Werdelin 1999). Interestingly, measurements of mandibular premolars 2,3 and 4 consolidate the taxonomic view adopted here on the basis of cranial and upper dentition features. Nonetheless, equivalent measurements of the upper premolar dentition in South African specimens

110

(Figure 9) remain within the extreme range of variability found in the Eurasian samples.

Revised diagnosis of PllCllycroclllo IJrepUoslris (Aymard, 1846)

Pachycrocuta brevirostris represents the largest known hyaenid, with an estimated skull length of around 300 mm (see Figure 1). According to Thackeray & Kieser (1992), an approximate body weight of 63 kg should be assumed based on lower carnassial length extrapolation. However, this weight appears to be underestimated, considering the fact that limb proportions indicate a shoulder height of 0.9 to 1 m (Turner & Anton 1996: 460). The size of the Pachycrocuta cranium presented in this paper suggests a markedly heavier body weight than proposed by Thackeray & Kieser (1992), but a lighter body weight than the approximately 125 kg of extant small female lions.

The skull is massive and broad, and the muzzle is comparatively short. Zygomatic arches are relatively short and broad. The tibia is proportionally shorter than the femur in comparison to extant hyaenids (Turner & Anton 1996: 460).

Not a single autapomorphic feature is currently held to be found in P. brevirostris. As a result of our analysis, we propose a group of presumably diagnostic dental characters: 1. p1 normally present, occasionally small; 2. p2 and p3 proportionally similar to Hyaena and

Parahyaena, less similar to Crocuta; 3. M1 present, large and only slightly obliquely

positioned in relation to p4longitudinal axis.

Apart from its taxonomic weight, the hyaenid dentition reveals important information concerning functional morphology and allows conclusions about palaeoecology. Some suggestions have been brought forward in the literature, and in the following section we comment on some of these aspects concerning P. brevirostris.

'"

1.350 1.300

1.250

~ 1 .200 at 1.150 - 1 . 100

1.050

x xx

+'.

x x

x 1.000 +-----1---t----+-----1

A

... Q.

1.200

1.450

1.400

;: 1.350

1.300

1.250 1.300 1.350

Ig LP2

x +

x

1.400

1.250 +-----+---+----...., c 1.520 1.570 1.620

Ig LP4

1.670

TABLE 2. Indices after Ewer (1954&). Comparison of mean values;

data based on Ewer (1954&), Ficcarelli & Torre (1970) and specimens. For discussion see the text.

1. 2. 3. 4. 5. 6. 7. 8. 9.

Hyaena hyaena

85.2 104.0 75.5 33.3 76.8 52.8

102.0 43.5 74.5

Crocuta crocuta

95.3 133.0 89.8 44.7 90.0 72.4

113.0 29.7 81.1

Parahyaena brunnea

88.1 104 84.2 35.2 81.0 53.8

104.0 47.7 74.4

Pachycrocuta brevirostris

88.3 109.8 84.2 37.9 84.5 62.5

108.9 42.6 82.5

Notes on functional morphology Ewer (1954a) has shown that the spotted hyaena

differs considerably in dental functional morphology from its smaller extant relatives. The relevant features are not 'absolutely diagnostic' (Ewer 1954a: 189), but represent an attempt to show tendencies and differences in functional morphology in both the 'hyaenoid' and 'crocutoid' specializations.

From this standpoint, the status of the P. brevirostris dentition has never been investigated in detail, although Kurten (1956) hinted at this important question. We here summarize the relevant features (Tables 2 and 3) as essentially defined by Ewer (indices 1-6 of the carnassial shear, indices 7-9 to show adaptation to crushing).

Comparison and interpretation of indices in Table 2 For the sake of clarifying ambiguity, the indices of

functional significance as defined and applied by Ewer (1954a: 190-191) are: 1. p4 length : combined lengths of p2+ p3 2. M1 length: P4length 3. Width across protocone : length of paracone +

metacone of p4 4. Metacone length: total length of p4 5. Blade length of M1 : total length of M1

1.350

1.300

~ 1.250 ;: ~ 1.200

1.150 c c 1.100 +-----+---+--_----1

B 1.300 1.350

1 .500 1.480

1.460 g 1.440

'" 1.420 - 1 .400

1.380

1.400 1.450 1.500

Ig LP3

+ x

X x'< x?< X x X x+'< x x X

x<

1 .360 +----+---+--_--...., 1.200

D 1.250 1.300 1.350

Ig LP2

1.400

Figure 9 A-C. Bivariate plots of premolar length/width and D. length P211ength P3 ratio in 19 (mm) of Pachycrocuta brevirostris. Taken from South African specimens (+: our data) and Eurasian specimens (x: from Turner & Anton 1996). Reference data is Crocuta crocuta (squares), most of which is omitted for clarity of illustration. See also Werdelin (1999: 162-164).

111

TABLE 3. Functionally interpreted morphology in the bone-cracking hyaenid dentitions. Based on Ewer (19548, 19S4b) and Kurten

(1988). For discussion see the text.

Hyaena Crocuta Parahyaena Pachycrocuta hyaena crocuta brunnea brevirostris

p4 slicing adaptation M 1 size reduction in

less specialized highly specialized less specialized intermediate moderately reduced strongly reduced reduced moderately reduced

relation to P p! orientation: bone sagittal chewing efficacy almost sagittal sagittal sagittal P 3fP 4 sliding contact absent present absent present P fP4 shear absent present absent absent or present M 1: form and function relatively shorter: tabloid relati vel y longer: relatively shorter: relatively shorter

chopping mechanism talonid functionless, talonid chopping talonid reduced metaconid lost

6. Blade length of M J : total length of p4 7. P3 width: P4 width 8. Parastyle length: length of paracone + metacone of

p 4

9. Width of p3 : width of p4 across protocone

1-6: These indices characterize efficiency of the carnassial blade. In all these indices P. brevirostris comes closest to the condition observed in P. brunnea, indicating the double function morphology of the chopping and slicing mechanism involving posterior premolars and molar.

7: The premolar accessory cusps are usually well developed in P. brevirostris, but there is also evidence which suggests considerable intraspecific variation. H hyaena and P. brunnea show signs of reduction in the anterior accessory cusp of p4 (Ewer 1954a: 191), whereas C crocuta does not. P. brevirostris has an intermediate character in this sense: the p4 works less efficiently as a crusher compared to Hyaena and Parahyaena, but more efficiently than in C crocuta.

8,9: These indices reveal that the crushing function of the upper premolar teeth is not as efficient as observed in P. brunnea, index 8 being closer to H hyaena but still far from the specialized condition developed in C crocuta. Index 9 reveals an even higher value in P. brevirostris than in C crocuta.

Admittedly, indices 7 and 9 are less appropriate for comparison, because the third premolar reflects rather the evolutionary level, as it has not yet reached the 'larger relative width' developed in younger taxa, as recognized by Qiu (1987). In our opinion, this diminishes the functional significance of these two indices. We conclude from the above that P. brevirostris was an efficient bone crusher but a less efficient meat slicer, compared to extant bone-cracking hyaenids.

Notes on body size, palaeoecology and behavior Some morphologies in the carnivore skull and

dentition are known to be directly correlated with body size (Kurten 1973; Werdelin & Solounias 1990) and can reflect its evolutionary changes (SoergeI1936; Kurten 1965). On the one hand, the body mass of the hyaena has been shown to be closely related to climatic change (Klein & Scott 1989; Thackeray & Kieser 1992), while

mechanism

on the other hand animal size is undoubtedly related to hunting ability and social behavior (Skinner, Davis & Ilani 1980; Hennig 1986). Considering its large size, dental morphology and limb proportions, the feeding habits of P. brevirostris may also be reconstructed on the basis of faunal analyses, which mirror the palaeoecological circumstances. Extant hyaenas are, aside from their opportunistic adaptation to scavenging, successful at killing prey. Bagged prey constitutes a variable but considerable percentage of their diet (see e.g. Tilson, Blottnitz & Henschel 1980; Skinner, Henschel & van laarsveld 1986; Cooper 1990; Henschel & Skinner 1990; Sillero-Zubiri & Gottelli 1992). Despite the fact that hyaenas are well known as taphonomic agents (e.g. Thenius 1961, 1976; Mills & Mills 1977; Lam 1992; Marean, Spencer, Blumenschine & Capaldo 1992), bones found in hyaena dens can be correlated with high accumulations of ungulate populations (Skinner, Henschel & van Jaarsveld 1986). On the basis of the fossil record, Werdelin (1989: 389) concluded from the relatively short distal limb bones that P. brevirostris was not adapted as a pursuit predator, and Turner & Anton (1996) suggested that the behavior of P. brevirostris may be comparable to C crocuta of the Late Pleistocene. In this context it is interesting that the Gladysvale D-8 deposits more frequently revealed equid remains than other early hominid-bearing sites in South Africa. This may possibly correspond with the occurrence of a bone-accumulating agent (Berger 1992, 1993), such as P. brevirostris.

This hypothesis is speculative at the present time, but it is testable through faunal analysis (see Sutcliffe 1970; Blumenschine 1988; Marean, Spencer, Blumenschine & Capaldo 1992) in a chronological framework provided by ESR-dating. By contrast, carnivore tooth attrition (Lindeque & Skinner 1984: 293) and an encephalization quotient (Sheppey & Bernard 1984) may be regarded as less promising approaches to the task of widening palaeoecological understanding.

ABBREVIATIONS Institutions AIUZ Anthropologisches Institut der Universitat

Zi.irich (Switzerland) BPI Bernard Price Institute for Palaeontological

112

NMB

PIMUZ

FIS

TMP ZMUZ

Research, University of the Witwatersrand, Johannesburg (South Africa) N aturhistorisches Museum Basel (Switzerland) PaHiontologisches Institut und Museum der UniversitatZUrich (Switzerland) Forschungsinstitut Senckenberg, Frankfurt (Germany) Transvaal Museum, Pretoria (South Africa) Zoologisches Museum der Universitat ZUrich (Switzerland)

Localities (South Africa) BF Bolt's Farm GV Gladysvale Cave KA Kromdraai M Makapansgat SK Swartkrans Sts Sterkfontein

Localities (France) Se Seneze St.V. St-Vallier

Locality (Italy) V.A. Vald'Arno

Measurements 1, length; w, width.

Morphology apf anterior palatine foramen bs basisphenoid c canine

dext. f gf if inf izf J M mx n P pI pm pop ppf pt ptf sin. sq zyg.

dextra frontal glenoid fossa incisive fossa infraorbital foramen incisive foramen jugal molar maxillary nasal premolar palatine premaxillary postorbital processes posterior palatine foramen pterygoid pterygoid foramen sinistra squamosum zygomatic (arch)

ACKNOWLEDGEMENTS We would like to thank Mike Raath (BPI), Francis Thackeray and

Heidi Fourie (both TMP), Gustav Anzenberger and Martin Hausler (AIUZ), Burkhardt Engesser (NHB), and Casar Claude (ZMUS) for assistance and/or access to specimens in their care. We are greatly indebted to Karl-Alban Hiinermann (Mellingen, Switzerland) and Michael Morlo (FIS) for expert advice and fruitful discussions. We also appreciate the support and patience of Hans Rieber and Thomas Bolliger (both PIMUZ), who commented on earlier versions of the manuscript. Misha Kavka kindly revised the English. The efforts of Ina Plug and Francis Thackeray are especially appreciated; certain errors would have been inevitable without their thorough review. This research was supported by the Swiss National Science Foundation (Grant No. 31-43584.95 to Peter Schmid), the Palaeo-Anthropological Scientific Trust, the National Geographic Society, the Adolph H. Schultz-Foundation, and the Georges & Antoine Claraz-Donation.

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